300 THE EVOLUTION OF THE METAZOA 



Yet before I begin an explanation of an outline of 

 the probable organization the animal had at the point of 

 separation of the lines of evolution of the Eumetazoa and 

 of Infusoria (an outline which can now be made with a 

 considerably greater precision) I would like first to call atten- 

 tion to the excellent and instructive work by Earl D. Hanson 

 (Hanson, 1958). 



I believe I am right when I state that Hanson has basically 

 accepted my concept, even if he did not accept it at first. 

 In his criticisms, expositions, additions, and ammendations 

 Hanson refers, when he discusses my arguments, to the 

 necessarily brief article only w^hich appeared in the Systematic 

 Zoolo^j (Hadzi, 1953). Hanson's leading idea is that my con- 

 cept cannot be accepted in its present form, that it still needed 

 some essential propping and complementing, above all the 

 point where I discuss the deduction of the Acoela from the 

 Infusoria. In his argument he states that, "The parallels bet- 

 ween the Acoela and the Ciliophora may be illusory, in terms 

 of demonstrating a phylogenetic relationship, if it turns out 

 that the acoel has its counterpart only in a fictional amalgam 

 of ciliate characters that has no more reality than the mythical 

 Chimera." I believe that with such a formulation Hanson has 

 gone much too far and that the formulation is inadequate. 

 The fact which is called by Hanson somewhat ironically an 

 "amalgam" or a "Chimera" is in reality a phenomenon which 

 has been earnestly studied by modern phylogenetics where 

 it is known under the name of the Mosaic theory, or Watson's 

 rule, as it has been called (Sir Gavin de Beer, 1954). An 

 "accidental" convergence of several characteristics of an 

 existing type can lead by way of genetic regulations to 

 new combinations (naturally with a simultaneous appearance 

 of new^ mutations). It is in this way that new animal types 

 which are able to live— and no chimeras — can develop and 

 in all probability also have developed. 



Moreover I \\-ish to remind the reader that at the begin- 

 ning of the present study I already said that I came to my 



